Why Are Certain Plants Dominant in Grasslands?
The land which is dominated by grasses rather than larger shrubs or trees is called Grassland. Approx 25 million years ago, mountains rose in western North America and created a continental climate favourable to grasslands. With the passing of time, ancient forests converted into grasslands. Majorly there are two types of grasslands are Savanna and Temperate grassland.
Origin of Grasslands
Grasslands that are most extensive in nature are thought to work as intermediates between an environmental gradient, with forests at one end and deserts at the other. As forests are mainly present in the area where there is an abundant amount of moisture for proper growth and survival of organisms. Whereas the areas which are desert in nature lack moisture and permanent vegetation is not found here. And the grassland found between these two regions.
Types of Grassland
A. Temperate Grassland: Areas, where grasses are the dominant vegetation, are called temperate grassland. In this area trees and large shrubs are absent. In this type of grassland, temperatures vary more from summer to winter and rainfall is very less in this area. Major areas of temperate grassland are veldts of South Africa, the puszta of Hungary, the pampas of Argentina and Uruguay, the steppes of the former Soviet Union, and the plains and prairies of central North America.
B. Tropical Grassland: In this grassland individual trees are tropical grassland. This type of grassland covers almost half the surface area of Africa along with large areas of Australia, South America, and India. Climate acts as a major factor in the tropical grassland. This grassland receives rainfall of approx 50.8 to 127 cm, per year. They are mostly found in hot or warm climates. Major plants here are tall grasses or short grasses.
FAQs on Grassland Dominant Plants Explained: Types, Roles & Examples
1. What are the dominant plants in a grassland ecosystem?
The dominant plants in any grassland ecosystem are species of grass (family Poaceae). These are often accompanied by a variety of non-woody, flowering plants known as forbs (e.g., wildflowers, legumes) and sedges. The specific species vary depending on whether the grassland is temperate or tropical.
2. What are some examples of dominant plants found in temperate grasslands?
Temperate grasslands, such as prairies and steppes, are dominated by grasses that are typically shorter than their tropical counterparts. Common examples include:
- Grasses: Buffalo grass, Blue grama, Purple needlegrass, and various Fescue species.
- Flowers (Forbs): Asters, blazing stars, coneflowers, goldenrods, clovers, and wild indigos.
3. Which plants typically dominate tropical grasslands like the Savanna?
Tropical grasslands, or savannas, receive more rainfall and are characterized by much taller grasses. Dominant plants include:
- Grasses: Elephant grass (which can grow up to 10 feet tall), Rhodes grass, Red oats grass, and Lemongrass.
- Scattered Trees: Unlike temperate grasslands, savannas often feature scattered, drought-resistant trees like Acacia and Baobab.
4. Why are grasses, and not large trees, the dominant form of vegetation in grasslands?
Grasses dominate over trees in grasslands due to a combination of key environmental factors. The primary reasons include:
- Rainfall Levels: Grasslands receive moderate rainfall, which is enough to support grasses but insufficient for the growth of a dense forest.
- Frequent Fires: Natural or human-made fires are common in grasslands. Grasses can survive and recover quickly from fire because their growth points are below the ground, while tree seedlings are typically destroyed.
- Grazing Pressure: Large herbivores graze heavily on young plants. Grasses are adapted to withstand grazing due to their low growth points, whereas young trees are often killed before they can mature.
5. How are dominant grassland plants adapted to survive their environment?
Grassland plants have developed remarkable adaptations to thrive in an environment with grazing, fire, and variable rainfall. Key adaptations include an extensive and deep root system, often with rhizomes, which helps them access water deep in the soil and regrow after being eaten or burned. Their growth tissues, or intercalary meristems, are located at the base of the plant, not the tip, allowing them to grow back quickly after their tops are removed by fire or a grazing animal.
6. What is the key difference between the vegetation of temperate and tropical grasslands?
The primary difference lies in the height and structure of the vegetation, driven by climate. Temperate grasslands have shorter grasses and are almost entirely treeless. In contrast, tropical grasslands (savannas) are defined by very tall grasses and the presence of scattered, fire- and drought-resistant trees. This is because tropical grasslands receive significantly more rainfall and have higher temperatures year-round.
7. What ecological role do forbs (wildflowers) play in a grassland ecosystem?
While grasses are dominant, forbs are essential for the health and biodiversity of a grassland. Their primary roles include:
- Supporting Pollinators: Their flowers provide nectar and pollen for bees, butterflies, and other insects.
- Enhancing Soil Health: Many forbs, especially legumes like clover and lupines, have root nodules that host nitrogen-fixing bacteria, enriching the soil.
- Increasing Biodiversity: They provide food and habitat for a wider range of insects and animals, contributing to overall ecosystem stability.
